Roll arrangement

ABSTRACT

A roll arrangement is described with a rotatable roll jacket, a fixed carrier and a multi-part support arrangement disposed between the roll jacket and the carrier and consisting of sliding shoes which are movable in the radial direction relative to the roll jacket. In this arrangement neighboring sliding shoes in the axial direction and/or in the circumferential direction of the roll jacket are biased towards one another groupwise in gap-free manner while maintaining relative movability.

BACKGROUND OF THE INVENTION

The invention relates to a roll arrangement comprising a rotatable,preferably flexible roll jacket, a stationary carrier and a multi-partsupport arrangement which is disposed between the roll jacket and thecarrier, with the roll arrangement including sliding shoes which aremovable in the radial direction relative to the roll jacket and havesupport surfaces facing the roll jacket.

Such roll arrangements are for example used for the treatment of paperwebs. It is extremely important, in particular in the smoothing of paperwebs, that the press force which is exerted onto the paper web by thesupport arrangements via the roll jacket is uniform over the width ofthe paper web. Even the smallest differences in the pressing force canlead to relatively large differences with respect to the smoothingeffect. In practice this means that the paper web has been smoothed todifferent degrees over its width after passing through the smoothingzone. Such differences represent deficiencies in quality which can makethe paper unmarketable.

A roll arrangement intended for the smoothing of a paper web is knownfrom DE 43 22 876 A1 in which support arrangements are used in the formof sliding shoes which can be pressed against the roll jacket and whichare built up from individual sections in the form of beams which followone another in the running direction. The beams can also be subdividedinto sections transverse to the running direction of the web. Use can bemade of either a single large pressing element which can act on theentire shoe consisting of individual sections, or of several pressingelements which are associated with the individual sections or portions.The aim of subdividing the sliding shoe into individual sections ofportions is to avoid distortion effects which can arise in a one-pieceshoe and which impair the smoothing quality, and also to maintain thegeometry of the smoothing zone even with changing operatingtemperatures.

In order to avoid the unavoidable partition gaps between the individualsections or portions leaving tracks in the paper web, provision is madein this known arrangement for the surface of the sliding shoe consistingof individual sections which faces the roll to be covered by a layerwhich forms the sliding surface and which is weak in bending and canconsist of a foil or of a piece of sheet metal.

With such a layer, which in other respects can only be used if nohydrostatic support of the roll jacket is required, it is not howeverpossible to avoid a loss of support at the gaps between the individualsections. A loss of support and oil in the region of the existing gapswhich results from the subdivision of the unitary sliding shoe intoindividual sections or portions has a negative effect on the pressingforce distribution transverse to the direction of running of the web andleads to deficiencies in quality of the respectively processed product.

SUMMARY OF THE INVENTION

The object of the present invention is to so design a roll arrangementof the initially named kind that the disadvantageous gap losses ofhydraulic fluid and thus of supporting force are avoided or are at leastlargely precluded.

This object is essentially satisfied in that neighboring sliding shoesin the axial direction and/or in the circumferential direction of theroll jacket are arranged in a gap-free manner and/or are mutuallyclamped together groupwise while maintaining relative movability.

Through the measures of the invention, a multi-part support arrangementis provided which behaves essentially as a one-piece support arrangementbut does not have its disadvantages with respect to the adaptability tothe respective roll jacket which can be designed from stiff to highlyflexible. The deficiencies of one-piece sliding shoes originating fromdistortion, thermal expansion or geometry errors which are alsodeleterious for the hydrodynamic or hydrostatic lubrication no longerappear in disturbing manner in the arrangement of the invention. Thus,in the practical use of such roll arrangements, surprisinglyadvantageous results can be obtained, in particular with respect to theuniformity that can be achieved or to the intentionally controllabledisuniformity of the press force distribution in the press gap. Thequality of a paper web processed by means of such a roll arrangement canthus be substantially increased.

Neighboring sliding shoes preferably do not contact one another overtheir full area but are rather only in contact with one another viaweb-like contact surfaces disposed at their support surface sides, sothat the clamping force which keeps the individual sliding shoestogether only enters into effect in the region of these comparativelysmall area contact surfaces. Should tilting tendencies arise betweenneighboring sliding shoes, this design ensures that the resultingtilting axis only has a very small spacing from the respective rolljacket and in this way only very small wedge gaps arise. In practicethese do not open towards the carrier and do not lead to any notableloss of hydraulic fluid and thus practically also to no drop in thepressing force.

The mutual clamping of the individual sliding shoes preferably takesplace by means of clamping wires which are guided through bores whichpass through the sliding shoes in the region of the contact surfaces.

A further advantage which arises when using this invention with jacketsthat are stiff in bending results from the fact that the requiredquantity of oil for the lubricating film is reduced by more than onehalf. This is in contrast to the situation with customary individualsliding shoes arranged spaced from one another because these lose oilover their entire support surface boundary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial longitudinal sectional view of a first embodiment ofa roll arrangement in accordance with the present invention;

FIG. 2 is a partial longitudinal sectional view of an alternativeembodiment of a roll arrangement in accordance with the presentinvention;

FIG. 3 is a plan view of a plurality of adjacent sliding shoes of a rollarrangement seen sectionwise;

FIG. 4 is a partial sectional illustration of two adjoining slidingshoes; and

FIG. 5 is a plan view of the contact surface of the right-hand slidingshoe of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS

In accordance with FIG. 1, a roll arrangement in accordance with thepresent invention includes a roll jacket, a stationary carrier 2 and asupport arrangement 3 provided between the roll jacket 1 and the carrier2.

The support arrangement 3 consists of several adjoining sliding shoes 5with respectively associated feet 4 which are formed in one piece withthe sliding shoes 5 or which can also be tiltably connected to thesliding shoes 5.

Each sliding shoe 5 has a support surface 6 associated with the rolljacket 1 which is shaped in approximation to the shape of the rolljacket 1. With corresponding flexibility of the roll jacket 1, thesliding shoes 5 can, if necessary, have a convex shape of the supportsurface.

The feet 4 of the sliding shoes 5 engage in a piston-like manner inpressure chambers 7, 8, 9 which are formed in the carrier 2. Sealingelements 10 are arranged in recesses 11 of the feet 4 and contact thepressure chamber walls.

The pressure chambers 7, 8, 9 can be individually pressurized with apressure medium via bores 12a, 12b, 12c provided in the carrier 2 sothat the supporting forces can be individually selected.

Respective neighboring sliding shoes 5 of the support arrangements 3 liedirectly against one another but not in full area contact. Instead theyonly contact one another via contact surfaces 13 disposed at the supportsurface ends. These contact surfaces 13 act as sealing surfaces and areclamped to one another in this contact state.

The contact surfaces 13 at which the clamping forces are effective aredesigned to have a comparatively small area and extend up to therespective support surface 6 so that a practically gap-free transitionis provided between the individual sliding shoes 5. The mutual clampingof the sliding shoes 5 admittedly continues to ensure relativemovability between the individual sliding shoes 5, which is necessary inorder to ensure the required high adaptability to the roll jacket 1, butit prevents relative mutual tilting to the extent that only very smallwedge gaps can arise which do not lead to any loss of oil and thus alsodo not lead to any loss of support force.

The required clamping forces are preferably generated by clamping wires15 which are led through mutually aligned bores which pass through thesliding shoes 5 in the region of the contact surfaces 13 and which canbe tensioned to the respectively required degree by means of suitabletensioning means 16, 17. This level of tension can be differentiallyselected in dependence on the operating circumstances, in particular independence on the lubricant pressure prevailing between the roll jacketand the sliding shoe.

The application of the respectively desired clamping force can also takeplace by hydraulic, pneumatic, electromagnetic, mechanical ormotorically actuated clamping means and can, if necessary, be modified,controlled or regulated in dependence on the operating conditions.

In order to ensure that the sliding shoe unit provided by mutualclamping of individual sliding shoes 5 is clearly positioned transverseto the running direction of the roll jacket 1, and also in the runningdirection of the roll jacket, the respective sliding shoe unit can becentrally fixed or, alternatively, fixed at one end, and can inparticular also be biased against an axial abutment 14 which is formedat the carrier side. The respective fixation of the sliding shoe unitdoes not thereby impair the relative movability of the individualsliding shoes 5 which are clamped against one another in a gap-freemanner.

The roll jacket 1 can be hydrostatically or hydrodynamically supportedin a known manner with respect to the support surfaces 6 of the slidingshoes 5.

Instead of an individual pressure loading of the individual slidingshoes 5 of a sliding shoe unit consisting of a plurality of mutuallyclamped sliding shoes 5, it is also possible for a uniform loading ofthe sliding shoes to take place since a sliding shoe unit of this kindis arranged in a common pressure trough in the manner of a one-piecesliding shoe.

An alternative embodiment of a roll arrangement in accordance with thepresent invention is shown in FIG. 2, and components of this embodimentare designated with the same reference numerals as the correspondingcomponents of the embodiment shown in FIG. 1.

The roll arrangement of FIG. 2 again comprises a roll jacket 1, a fixedcarrier 2 and a support arrangement 3 provided between the roll jacket 1and the carrier 2. The support arrangement 3 consists of a plurality ofsliding shoes 5 which are clamped together over their contact surfaces13 by means of a clamping wire 15 and suitable tensioning means 16, 17and are thus combined into a sliding shoe unit.

In contrast to the embodiment of FIG. 1, the feet 4 associated with thesliding shoes 5 do not directly engage in recesses of the carrier 2while forming piston-in-cylinder units but rather multi-part feet 4 areused.

The feet 4 consist, in the embodiment of FIG. 2, of a preferablycylindrical sliding shoe projection 19a which engages into acorresponding recess of the intermediate part 19b while forming apiston-in-cylinder unit 19. Each of the intermediate parts 14b issupported via a tilting bearing 24 with spherical support surfaces on abase part 25 which is preferably displaceably supported on the basesurface of a recess 18 of the carrier 2 which extends in the axialdirection of the roll jacket.

Through the provision of a tilting bearing 24 and the freedisplaceability of the base part 25 on the carrier 2, the possibilitiesof adaptation of the sliding shoes 5 to the deformations of the rolljacket are further improved and it is ensured that neither disturbingstresses within the sliding shoe unit consisting of a plurality ofsliding shoes 5 nor differential extensions can occur becausecorresponding compensation movements are ensured in the region of thetilting journal 24 and through displacements of the base part 25relative to the carrier 2.

The piston-in-cylinder units 19 which, if necessary, can be combinedwith a mechanical prestressing unit acting in the same direction havetheir pressure spaces 20, 21, 22 connected with pressure medium bores12a, 12b, 12c and can be energized with pressure fluid individually asin the case of the pressure space 20, or groupwise, as in the case ofthe pressure chambers 21, 22.

In their support surfaces 6 the sliding shoes 5 have pressure pockets 23which can be supplied with a hydraulic fluid for the hydrostatic supportof the roll jacket 1. In the illustrated embodiment the pressure pockets23 are connected for this purpose to the pressure chambers 20, 21, 22 ofthe piston-in-cylinder units 19 via throttling supply bores 23a.

FIG. 3 shows in plan view a group of sliding shoes 5 of a rollarrangement arranged adjacent to one another in accordance with theinvention, with the sliding shoes 5 being arranged alongside one anotherin the axial and in the circumferential direction of the roll jacket.Specifically, three rows of sliding shoes extending in the axialdirection are provided alongside one another in the circumferentialdirection with the sliding shoes 5 being arranged mutually displaced toone another.

FIG. 3 shows simply schematically by way of arrows that the slidingshoes 5 are clamped against one another both in the axial direction andalso in the circumferential direction of the roll jacket. Moreover,fixed points can be provided by non-illustrated axial and/orcircumferential abutments which ensure an unambiguous positioning of theso-formed sliding shoe unit.

It should also be mentioned that flow channels for a suitable fluid canbe provided which extend through the sliding shoes 5 for the provisionof temperature compensation within the respective sliding shoes.

It is likewise possible to provide a hydrodynamic support with respectto the sliding shoes 5 in place of the hydrostatic support of the rolljacket shown in FIG. 2 without this affecting the basic principle ofsliding shoes mutually clamped together groupwise in a gap-free mannerwhile maintaining relative movability.

FIGS. 4 and 5 show that the contact surfaces 13 between the adjacentsliding shoes 5 need not be made flat over the full area but rather thatrecesses 28 can be provided in at least one of the two contact surfaces13.

In accordance with the variation of FIGS. 4 and 5, one of the contactsurfaces 13 is so formed that the areal contact between two adjacentsliding shoes is only small, which has the consequence that on buildingup a hydraulic pressure only a small force is obtained which could pressthe sliding shoes apart from one another. At the same time the contactsurface 13 is so designed that with a relative displacement of thecontacting surfaces, these cannot hook into one another.

The recess 28 in the contact surface 13 is so designed that the web 29which results at the jacket side is very narrow while the web 30 at thecarrier side can have a comparable dimension or could also be madebroader. As a non-restrictive example, it is mentioned that the web atthe jacket side can have a width of approximately 1 mm.

The recess 28 is subdivided by vertical webs 26 and passages 27 areprovided in these webs 26 which ensure a connection between theindividual part regions of a recess 28 in the surface 13. Because ofthese passages 27 no hydraulic pressure can build up in the chambers 28and on the webs 26 and 30.

It has already been mentioned that recesses such as the recess 28 ofFIG. 5 can be provided in the two cooperating contact surfaces 13;however it is also sufficient if only one of the contact surfaces hassuch a configuration as shown in the FIGS. 4 and 5.

In accordance with FIG. 4 each sliding shoe 5 is provided with anundercut adjoining the respective contact surface 13, however it wouldbe entirely sufficient to provide such an undercut only in one of thetwo cooperating sliding shoes 5, which represents a simplification fromthe technical manufacturing viewpoint.

What is claimed:
 1. A roll arrangement comprising a rotatable rolljacket, a stationary carrier and a multi-part support arrangement whichis disposed between the roll jacket and the carrier, with the rollarrangement including sliding shoes which are movable in a radialdirection relative to the roll jacket and have support surfaces facingthe roll jacket, wherein neighboring sliding shoes in an axial directiondefined by an axis of rotation of the roll jacket are clamped againstone another groupwise in a gap-free manner while maintaining relativemovability thereof.
 2. A roll arrangement in accordance with claim 1,wherein neighboring sliding shoes only contact one another at theirsupport surface ends in a region of web-like contact surfaces and arespaced apart at the carrier side.
 3. A roll arrangement in accordancewith claim 2, wherein the contact surfaces of neighboring sliding shoesare planar.
 4. A roll arrangement in accordance with claim 1, whereinneighboring sliding shoes along a circumferential direction of the rolljacket are arranged such that they are displaced in the axial directionof the roll jacket.
 5. A roll arrangement in accordance with claim 1,wherein a radial extent of contact surfaces is smaller than a radialextent of the oppositely disposed spaced apart walls of sliding shoes.6. A roll arrangement in accordance with claim 1, wherein resilientelements which pass through the sliding shoes and are kept in tensionare provided for the mutual clamping of the sliding shoes.
 7. A rollarrangement in accordance with claim 6, wherein the resilient elementsare clamping wires that are guided through mutually aligned bores whichpass through the sliding shoes in a region of contact surfaces.
 8. Aroll arrangement in accordance with claim 1, wherein pneumatic,electromagnetic, mechanical or motorically stressed clamping means areprovided for applying the clamping force.
 9. A roll arrangement inaccordance with claim 1, wherein an amount of force with which thesliding shoes can be clamped against one another is variably adjustable.10. A roll arrangement in accordance with claim 1, wherein the slidingshoes are fixed at one end against displacement in the axial directionof the roll jacket and are clamped against an axial abutment.
 11. A rollarrangement in accordance with claim 1, wherein neighboring slidingshoes along a circumferential direction of the roll jacket which areclamped against one another are secured against displacement in thecircumferential direction of the roll jacket by a peripheral abutment.12. A roll arrangement in accordance with claim 1, wherein a foot isassociated with each sliding shoe and forms a hydraulically orpneumatically loadable piston-in-cylinder unit together with a surfaceon the carrier.
 13. A roll arrangement in accordance with claim 12,wherein the piston-in-cylinder units can be pressurized individually.14. A roll arrangement in accordance with claim 1, wherein pressurepockets are provided in the support surfaces of the sliding shoes forhydrostatic support of the roll jacket and are pressurized with ahydraulic medium.
 15. A roll arrangement in accordance with claim 1,wherein a hydraulic medium is supplied to the support surfaces forhydrodynamic support of the roll jacket.
 16. A roll arrangement inaccordance with claim 1, wherein the support surfaces have a concaveshape.
 17. A roll arrangement in accordance with claim 1, wherein flowchannels for a temperature compensation fluid are provided in thesliding shoes.
 18. A roll arrangement in accordance with claim 1,wherein groups of mutually clamped sliding shoes are respectivelyarranged in a common pressure trough in a manner of a multi-part pistonof areal design.
 19. A roll arrangement in accordance with claim 1,wherein at least one outwardly open recess is provided in at least onecontact surface.
 20. A roll arrangement in accordance with claim 19,wherein the recess in a contact surface is subdivided by at least oneweb into individual regions with the individual regions communicatingwith one another via a passage in the respective web.
 21. A rollarrangement in accordance with claim 19, wherein a web which bounds therecess at the jacket side is of very narrow design and its width isapproximately 1 mm.
 22. A roll arrangement in accordance with claim 20,wherein the passage formed in the respective web is provided adjacent toa jacket side web.
 23. A roll arrangement in accordance with claim 1,wherein the sliding shoes are flat.
 24. A roll arrangement in accordancewith claim 1, wherein a flexible cloth is provided as the roll jacketwhich adapts to the contour of a respective counter-roll.
 25. A rollarrangement in accordance with claim 1 wherein the rotatable roll jacketis flexible.
 26. A roll arrangement in accordance with claim 1 whereinthe neighboring sliding shoes are neighboring in a circumferentialdirection defined by the roll jacket instead of neighboring in an axialdirection.
 27. A roll arrangement in accordance with claim 26 whereinthe neighboring sliding shoes are also neighboring in an axial directiondefined by an axis of rotation of the roll jacket.
 28. A rollarrangement in accordance with claim 2 wherein the neighboring slidingshoes sealingly contact one another.
 29. A roll arrangement inaccordance with claim 1 wherein the sliding shoes are fixed at thecenter against displacement in the axial direction of the roll jacketand are clamped against an axial abutment.
 30. A roll arrangement inaccordance with claim 1 wherein the neighboring sliding shoes along acircumferential direction of the roll jacket which are clamped againstone another are biased against a peripheral abutment.
 31. A rollarrangement in accordance with claim 1 wherein a foot is associated witheach sliding shoe and forms a hydraulically or pneumatically loadablepiston-in-cylinder unit together with a base element supported on thecarrier, with the base element preferably being displaceably journalledrelative to the carrier.
 32. A roll arrangement in accordance with claim12 wherein the piston-in-cylinder units can be pressurized in groups.33. A roll arrangement in accordance with claim 14 wherein the pressurepockets are pressurized with the hydraulic medium from pressure spacesof the piston-in-cylinder units.
 34. A roll arrangement in accordancewith claim 1 wherein the support surfaces have a convex shape.
 35. Aroll arrangement in accordance with claim 1 wherein the sliding shoesare convex.
 36. A roll arrangement in accordance with claim 1 whereinthe sliding shoes are concave.